Guidewire loaded stent for delivery through a catheter

Abstract

A guidewire loaded stent for delivery through a catheter is described herein. The stent delivery assembly can deliver and place a stent within tortuous regions of the body which are accessible to guidewires but inaccessible to stenting catheters. The assembly comprises a guidewire covered in part by a retractable sheath and a radially expandable stent near or at the distal end of the guidewire. The whole assembly is advanced through conventional catheters or it may be used alone. In either case, when the stent is adjacent to a treatment site within the body, the sheath is retracted proximally to expose the stent for radial expansion into contact with the vessel wall. Radio-opaque marker bands are optionally located on either side or both sides of the stent on the guidewire body to aid in visual placement. The assembly can optionally include an expandable balloon on the guidewire for different treatment modalities.

1. A stent delivery assembly comprising:
 an elongate guidewire having a proximal end, a distal end, and a length therebetween and a reduced diameter portion to receive a stent thereon; 
 a radially expandable stent positioned coaxially on and in direct contact with the reduced diameter portion of the guidewire towards the distal end such that the stent can be placed by and moved by the guidewire; and 
 an elongated tubular sheath member covering at least a portion of the guidewire, the sheath having an internal elongated lumen terminating in a distal opening to freely slide over a portion of the length of the guidewire and over a portion of the length of the stent, the sheath being retractable from a first position where the stent is covered by the sheath to a second position where the stent is uncovered such that the stent is unhindered during sheath retraction, the sheath having a diameter greater than a diameter of the guidewire to receive the guidewire therein during movement, the stent positioned on the reduced diameter portion of the guidewire to accommodate the tubular sheath as it passes thereover. 
 
   
   
     2. The assembly of  claim 1  further comprising a coil disposed at the distal end of the guidewire. 
   
   
     3. The assembly of  claim 2  wherein the coil is radio-paque. 
   
   
     4. The assembly of  claim 1  further comprising at least one radio-paque marker band located on the guidewire proximally or distally of the stent. 
   
   
     5. The assembly of  claim 1  wherein the radially expandable stent is comprised of a radio-paque material. 
   
   
     6. The assembly of  claim 1  wherein the radially expandable stent is comprised of a shape memory alloy. 
   
   
     7. The assembly of  claim 1  wherein the sheath further comprises a flush port located near a proximal end of the sheath, wherein the flush port is in fluid communication with a distal end of the sheath. 
   
   
     8. The assembly of  claim 1 , wherein the stent is releasably connected to the guidewire proximal of a distalmost tip of the guidewire. 
   
   
     9. The assembly of  claim 1 , further comprising a stop on the guidewire, the stop having a height less than an internal diameter of the sheath, the sheath being passable over the stop. 
   
   
     10. The assembly of  claim 1 , wherein the stent is positioned inside the sheath so the sheath covers the outer surface of the stent during insertion of the assembly. 
   
   
     11. A stent delivery assembly comprising:
 an elongated guidewire having a proximal end portion, a distal end portion, and a intermediate portion between the distal and proximal end portions and configured to be directed to a surgical site, the guidewire having a reduced diameter portion to receive a stent; 
 a stent expandable from a constrained first configuration for delivery to the surgical site to a larger expanded second configuration, the stent mounted coaxially on the guidewire at a position spaced proximally of a distalmost tip of the guidewire so that positioning of the guidewire carries the stent to position the stent at the surgical site; and 
 a sheath covering a least a portion of the stent and having an internal diameter greater than an outer diameter of the stent in the first configuration, the sheath and guidewire being relatively movable to expose the stent to enable movement to the expanded second configuration, the sheath having a longitudinal lumen terminating in a distal opening, the distal opening being circular and with an internal diameter dimensioned to accommodate during relative movement an external diameter of the stent and guidewire for freely slidable relative movement, the stent mounted on the reduced diameter portion of the guidewire to accommodate relative movement of the sheath. 
 
   
   
     12. The assembly of  claim 11 , wherein the stent is releasably connected to the guidewire. 
   
   
     13. The assembly of  claim 11 , wherein the stent is comprised of a shape memory alloy. 
   
   
     14. The assembly of  claim 11 , further comprising at least one radio-paque marker on the guidewire. 
   
   
     15. The assembly of  claim 11 , further comprising first and second stops on the guidewire to maintain the stent in position on the guidewire, the stops dimensioned to fit inside the sheath to accommodate the sheath when the sheath is positioned thereover. 
   
   
     16. The assembly of  claim 15 , wherein the first and second stops each have a diameter less than a diameter of an intermediate portion of the guidewire. 
   
   
     17. The assembly of  claim 15 , wherein the stent is axially spaced from the first and second stops and unattached thereto to provide a gap therebetween so the stent can slide between the stops. 
   
   
     18. A stent delivery assembly comprising:
 an elongated guidewire having a proximal end portion and a distal end portion and configured to be directed to a surgical site; 
 a stent expandable from a constrained first configuration for delivery to the surgical site to a larger expanded second configuration, the stent mounted coaxially on the guidewire at a position spaced proximally of a distalmost tip of the guidewire so that positioning of the guidewire carries the stent to position the stent at the surgical site; and 
 a sheath covering a least a portion of the stent and having an internal diameter greater than an outer diameter of the guidewire, the sheath and guidewire being relatively movable to expose the stent to enable movement to the expanded second configuration, the sheath having a longitudinal lumen terminating in a distal opening with an internal diameter dimensioned to accommodate during relative movement an external diameter of the stent and guidewire for freely slidable relative movement; and 
 a stop on the guidewire, the stop having a height less than an internal diameter of the sheath and dimensioned to fit within the sheath to accommodate the sheath when the sheath is positioned thereover. 
 
   
   
     19. The assembly of  claim 18 , wherein a proximal end of the stent is axially spaced distally from the stop to provide a gap therebetween. 
   
   
     20. The assembly of  claim 18 , wherein the guidewire includes a reduced diameter portion and the stent is mounted on the reduced diameter portion of the guidewire to accommodate relative movement of the sheath.